Rheostat



Patented Sept. 23, 1930 PATENT, OFFICE THOMAS RHODUS, OF CHICAGO,ILLINOIS Application filed November 4, 1926. Serial No. 146,115.

This invention relates to that type of rheostats in which a curved coresupports a spiral winding of resistance wire to constitute thestationary member of the appliance, with the socompanion adjustablecontact member having movement in a curved path and in contact with suchwinding, an example of which is shown and described in my formerapplication Serial No. 7 6,141, filed Dec. 18, 1925. 10.And-thevariousobjects of the present improvements are To provide a structuralformation and combination ofparts whereby the curved supporting corewith its winding of resistusance wire has supporting connection with awall of the enclosing casing in a simple, substantial and insulatedmanner.

To provide a simple and effective formation and association of parts,wherein the curved supporting core with its windings of resistance wireis held in its proper and normal position Within the enclosing casingand in proper operative relation to the companion movable contactmember.

To provide a simple and effective formation and association of parts"wherein the curved supporting core of the resistance wire and the wallof the enclosing casing of the rheostat are penetrated in an insulatedmanner by the current carrying means and held thereby in workingrelation.

To provide a simple and effective formationa'nd association of parts,wherein the resistance member comprising a curved supporting core andits windings of wire is held in proper and normal position and in properinsulated operative relation to the companionv movable contact member,allas will hereinafter more fully appear.

In the accompanying drawing v Fig. l'is atop or plan view of'a rheostatembodying the invention, with parts of the enclosing casing broken awayand with parts in section. Fig. 2, is a sectional elevation on line 2-2Fig. 1. a

Fig. 3, is a detail section on line3-3 Fig. 1. Like reference numeralsindicate like parts in the different views.

In the construction shown, the enclosing shell or casing affords anenclosure and the sole supporting means for the rheostat parts, and tosuch end preferably comprises a circular wall 1 to the upper and lowerends of which are secured orificed closure heads 2 and 3 adapted toprotect the rheostat parts and afford proper ventilation. In the presentimprovement the rheostat parts are mounted in said enclosing casing andare'of a detail construction as follows.

r The stationary resistance element is preferably of the formationdescribed in my prior Patent No. 1,230,221, of June 19, 1917 andcomprises a series of open and flat spiral windings 4c of wire woundupon a curved insulating core 5 preferably of the split ring type, withthe ends 6 thereof formed to overlap and having aligned orifices for thepassage of the screw bolt 11 which in the preferred construction is aterminal post and the holding and current carrying means of the presentimprovement. Insulating material is arranged between the outer face ofthe overlap ends 6 of the core 5 and the inner face of thecircular wall1 of the enclosing casing and preferably of the form of an interveningorificed block 7.

Insulating material is arranged in aligned relation to said block 7 andin bearing contact with the'inner face of the overlap ends 6 of thesupporting core 5 aforesaid and preferably in the form of an inner block8 of a counterpart orificed formation to'that of-the block 7 aforesaid.Insulating material is arranged in aligned relation withblocks 7 and 85.8 and in bearing contact with the outer face of the wall 1 of theenclosing casing of the rheostat and preferably in the form of an outerblock 9 ofa counterpart orificed formation to the blocks 7 and 8aforesaid.

In the construction shown, the bolt 11 is insulated from the wall 1 ofthe casing and from the curved core 5 of the resistance element, and inthe preferred construction, a tubular sleeve 10 of high insulatingmaterial extends through theorifices of the plurality of blocks 7 8 and9and through orifices of the Wall land of the overlap core ends 6, toprovide an. insulating encasement for preferably the shank of a screwbolt 11, by which the parts are drawn and firmly secured together.

In the preferred construction, the screw bolt 11 constitutes'both aholding means and a current carrying means: the outer end of the screwbolt 11 carries the usual pair of adjustable nuts 12 for effecting. theusual tightening or clamping. action of the bolt, and in additionconstitutes the attaching terminal or terminal post for one of the linewires of the circuit in which the rheostat is used; and the inner end ofthe bolt 11 is provided with the usual fixed head adapted to secure thejournal and supporting bracket 13- of the movable contact member of therheostat in place upon the; inner face of the aforesaid; nsulat nab cckh the. said-fix d a of the bolt 11 inelectric contact with the adjacentportion, Of said bracket 13. v

The journal and supporting bracket 13 abone referred to .is preferablyformed from a strip of plate meta-1 and bent, to an, angular form, withits respective arms formed with orifices, One of saidorificesisadaptedto re ceive the shankof the screw bolt 11 aforesaid, while the otherorifice, which is positioned in centraljrelation to the. curve of thecore 5 aforesaid, provides a journal bearing for the carrying shaftofthemovable contact memher now to be described.

The said movable contact member of the; rheostat is; preferably in theform of a revolubl'e roller 14, resiliently mounted; on a. centralcarrying shaft 15 journalled in the above described orifice in the.bracket 13,

and with suclrmountingpreferably comprismg a guide; head 15 finedon theend of. the shaft 15 and having guide ears for a sliding arm 17 on theouter end of which is journalledthe aforesaid contact roller 14.Associated with said guide. head 16 and sliding arm 17, 1s a compressionSPI'lIig; 18, the tendency of wh ch is to move the arm 17outwardsandmaintain; the roller 14 in contact w th the resistance,winding 4 of the stationary res stance member ofthe rheostat,

and in such; constructionthecontact roller 14,,guidehead l6and arm 17;are formed of metal or like conducting material.

At itsotherand upper end the carrying shaft 15 is provided with anoperating hand le ,'or;.knob 19 the lower end of'whichis preferablyformed with a reduced circular neck adapted for bearing engagement; in acentral orificeinthe'upper head 2 of the enclosing; casing of therheostat.

The other and companion terminal post for the attachment of the other.vline wireof the, circuitin which the rheostatis arranged,

is; of, a substantially counterpart construc.

tion te the terminal post; 11- above described and has-adjacentrelation; thereto as; shown, andpreferably comprises a screw bolt 20provided with an insulating sleev e 21 and a pair of. adj stable nuts:22, whi h n onnection with a pair of orificed abutment blocks 23, and anorifice in the wall 1 of the enclosing casing through which the saidsleeve 21 passes, provides an insulating mounting for such companionterminal post with its screw bolt 20 electrically connected to the endof the resistance winding 4 opposite to. the end of such winding whichhas. connection with the first mentioned terminal post.

Another part of this invention involves an enclosing means for the abovedescribed terminal posts, adapted to afford ready and convenient accessto the same and'to such end comprises a wall 24 of preferably platematerial'of preferably an approximately U shape, provided. withattaching flanges 25 at its respective ends bywhich it issecured byscrew bolts or like fastening means to the: wall 1 of the enclosinghousing of the rheostat. The wall .24 and, preferably the. crownportionof said Uv shaped wall 24 is. formed with, a. receiving orificev throughwhich the cable carrying theline wires,- of.

Auiotherpart of this invention involves means. for supporting thecarrying core. 5,

and its windings 4 of resistance wire in proper position with relationto the enclosing casing and the movable contract member of the rheostat,and to such end comprises preferably a plurality of blocks 30 havingre-' cesses of insulating material and preferably Lshaped, arranged in.the upper and lower. corners of the enclosing casing of the rheostat,with the recesses of said blocks.- forming saddles or rests and.abutments for, the: core 5 and its windings aforesaid, Inthe,

construction shown, a pair of said saddle blocks; of I insulatingmaterial engage the, upper edgeof the, core 5, and a single saddle,block in staggeredrelation to said pair of blocks, engagesthe lower edgeof the "core, 5; Lateral shift; or displacementofthesaddle blocks 30 is.prevented preferably by a pair of holding prongs 31 to each block 30,with said prongs preferably formed. by slitting the. plate metalheads 2and 3. ofthe enclosing casing to form said prongs, which are then bentinto parallel relation to; receive,

a saddle block between them. I

I Having thus fully describedmy invention,

what I claim and desire to secure by Letters;

Patent is 1. In a rheOStat, the, combination, of an enclosing casinghaving aside wall formed With an orifice, a stationary resistance:member of a curved sha e and having an orifice, an orificed blockinsulating material arranged between the orificed part of the resistancemember and the orificed side wall of the enclosing casing, a secondorificcd block of insulating material arranged on the inner side of theorificed part of the resistance member, a third orificed block ofinsulating material arranged on the outside of the orificed side wall ofthe enclosing casing, an L shaped bracket, one arm of. which has contactwith the second orificed block aforesaid and is formed with an orifice,a screw bolt passing through said ori- IS fices and attaching the saidparts together,

a sleeve of insulating material encasing a portion of the shank of saidbolt, an adjustable current carrying contact member making contact uponthe stationary resistance member, an orifice in the other arm of theaforesaid bracket, and an operating shaft for said adjustable contactmember having bearing in said last mentioned orifice.

2. In a rheostat, the combination of a re 3 sistance member of a curvedshape and having an orifice, a current carrying bracket having two armsone of which has an orifice,

a terminal screw bolt passing through the aforesaid orifices andattaching said parts i w together, a movable contact member makingcontact with said resistance member, a guide member comprising a centralportion and two arms, said movable contact member being supported bysaid guide member, and a carrying shaft associated with the other arm ofthe aforesaid bracket and having contact with the center portion ofsaidguide member at a point between the inner ends of the arms of said guidemember, the arms of 40 said guide member extending parallel to saidshaft.

Signed at Chicago, Illinois, this 1st day of November, 1926.

THOMAS RHODUS.

